Tire deflation indicator



Aug. 24, 1948. A. J.- SLOVACK TIRE DEFLATION INDICATOR Filed April 25, 1946 2 Sheets-Sheet 2 INVENTOR ALVIN JACK SLOVACK Patented Aug. 24, 1948 U N ITE D STAT E S PAT ENT O F Fl C E TIRE DEFLATION INDIGATOR Alvin J. Slovack, Houston, Tex.

Application April 26, 1946, Serial No. 665,117

1 Claim. 1

This invention relates to means for indicating the degree of inflation of pneumatic tires.

An object of the invention is to provide means that can be readily installed on a tire wheel of an automobile or truck, for automatically warning the driver of the vehicle when the air pressure in the tire has decreased below predetermined limits.

Another obl'ect of the invention is to provide means that can be readily installed in a vehicle, for warning the driver when the air pressure in any one or more of its tires has increased beyond predetermined limits.

A further object of the invention is to provide automatic tire inflation and deflation means that are readily installable in a vehicle without extensive alterations, and without the use of cumbersome devices which might interfere with the eilicient operation of the vehicle, and that may be manufactured at reasonably low cost.

Other objects and advantages of the invention will become apparent from the following description of a preferred embodiment thereof as illustrated in the accompanying drawings, and in whidh- Figure 1 is a fragmentary sectional elevation taken on a vertical plane containing the axis of a wheel, with the invention installed.

Figure 2 is a fragmentary sectional elevation in detail of a portion of the mechanism shown in Figure 1.

Figure 3 is a sectional elevation in detail of the brush contact device shown in the lower left corner of Figure 1.

Figure 4 is a sectional elevation of a front wheel grease retainer with built-in collector ring.

Figure 5 is a sectional elevation of an -indicator especially suited for indicating excess tire pressures, and having means for releasing such excess pressure, and

Figure 6 is a sectional elevation in detail, of the pop-off valve shown in the upper left corner of Figure 5.

Referring to the drawings, Figure 1 shows a tire casing 2 with an inner tube 4 mounted on the rim 6 of a Wheel generally indicated at 8, the rim 6 having outer flanges I and a peripheral groove l2. A web l4 connects the rim 6 with a wheel hub I which is secured by bolts 'lt'onto a brake drum 2D engageable on its inner surface by a brake lining 22 in the usual manner. The

drum 2!! is carried rotatably on an axle 2-4,-a hub cap 25 being provided, for covering the PIOj'BClGlllg axle 24.

The rim 6 has an aperture 28 formed in groove 2 I'Lthrough which extends a light metal externallythreaded hollow cylindrical stem 30 held in the aperture by upper and lower nuts 32 and 34 threaded onto the stem; An axial bore 36 in the stem'is reduced at its upper end through which is inserted a reduced lower portion of a plastic bushing 38 having a central axial bore; the enlarged upper portion of the bushing being held in position on the upper end of the stem 30 by an axially apertured flange nut 40 threaded onto the stem 30 A rubber inflatable diaphragm member 42 has a chamber 44 with "an aperture '48 formed in the wall of the member 42," the upper end of the stem 30 extending into the aperture '46 and the chamber 44 as-shown, the "edges of the aperture 46 being clamped tightly and sealedbetween the flange nut 40 and the nut 32.

A plunger head 48 is pressed against the upper inner wall surface of the diaphragm member :42 by a spring 50* acting between the head 48 and the flange nut 40. A rod 52, secured at its upper end to the plunger head 48, extends downward through the flangenut-N, the insulating bushing 38- and into the stem bore 36, its lower end 54 being formed into a point having side apertures 56 through which are sl-idable the upper ends 58 of a brass hair spring fifl'secured at its lower ends to the pointed end 5'4 of the rod 52 by soldering or otherwise, A coil spring 62 is soldered at its upper end to the pointed end and is soldered at its lower end to the enlarged head of a valve pin- 64 movably seated in and sealing the axial bore of an insulating bushing 66 threaded into the threaded portion of axial bore 36 in the stem.

The lower end of pin 64 has soldered to it a spring -58 soldered at its lower end to a contact member "HI extendin through an insulating cap 12 threaded onto the lower end of the stem 30 and. provided with a sealing washer 14.- The lower end of contact member 70 is rounded-to receivea spring clip 16 connected to a wire-"l8 extending through an aperture in the wheel hub 16 and into an insulating bushing 82 set in a bore in the *hub '86 of the brake drum. The bushing 82 is enlarged at '85 and has an axial bore 86 in which is slidable a contact plunger or brush '88 biased to protrude from the bore by a spring 90; the plunger 88"an-d wire "being electrically connected.

Flange 92 has secured to its outer surface an insulating ring 94 having an annular metal collector ring 96 in position so that rotating con-- tact plunger 88 bears against thecollector ring as it revolves. The collector ring 96 is connected by a wire 98 which extends through an aperture -the wall of the stem 30.

or other suitable member.

electrical contact.

3 I to a suitable lamp or other electrical indicating device actuated by current passing through wire 98.

As shown in Figure 4, a front wheel grease retainer I 02 may be formed of plastic fibre or other suitable material, with an insulating base ring I04 secured around its neck I06 by means of screws I08, with an insulating ring I'I0 having an annular recess for the reception of a metal collector ring H2, which has a wire II4 leading therefrom similarly to wire 98 in Figure 1. When the device shown in Figure 4 is used, the angle,

along which the plunger 88 presses would pre'ferably be changed to bear evenly on:collector"' ring I I 2, It will thus be observed that as plunger head 48 moves downwards responsive to-movement of the tube Wall 4, the pointed end 54 of the rod 5'2 4 I64 extends loosely through the bore I62, with its upper end I66 biased by spring I61 to seat on the conical upper end of the bore I62, a rubber gasket I68 providing a tight seal. Casing I 10 and cap I12 hold the spring I61 in place, the cap I12 having an air outlet hole I14. A rubber gasket I16 forms a tight seal and seat for the lower enlarged end I18 of the plunger I64, which has air passage holes I80, and has a downward projection I82 for depressing the pin I58 of the valve to give air out of chamber I 24 access to plunger I64.

When the air pressure in the tire and hence in chamber I2 4 is too great, plunger I64 is pushed is pressed down into the insulating bushing 66,

the ends 53 of the spring 60 being compressed into the apertures 56 as it descends, thus breaking the electrical contact of the sp'ring60 with As the plunger 48 rises responsive to movement of tube wall 4, it pulls the pointedend 54 out of the insulating bushing '66, allowing the spring 6M0 expand into electrical contact with the'stem 30, and lighting to an indi" cating lamp connected in the circuit with wire 18 and a source of power such as a battery.

Shown in Figures 5 and 6 is a device'suitablc for indicating excess pressures in auto truck tires due to overloading, over-inflation, high ambient temp'eraturaor high speeds. This device has a housing II6 comprising oppositely dished halves -'II8 and I20 joined at their edges, and having a 1 rubber diaphragm I2I separating the chamber I22 into two chambers I 24 and I26, the diaphragm being clamped between the edges of the dished halves toform a'tight seal. An air hose-I28leads into chamber I24 and has a threaded fitting I30 for engaging over the tire tube valve cap of a tire so as to depress the valve pin of the tube valve and allow air from the tire tube to flow freely into chamber I24.- A metal bushing I32, having an axial bore I'34, extends through an aperture I36 in dished half I20.

An insulating bushing I38 having a recess I38 is threaded into the bore I34, With'an end cap 239'threaded onto bushing I32 for closing its "end. A rod I40 is secured at one end to'the diaphragm I2I and is enlarged at its other end to for-rn a point I42 carrying and'connecte'd toa contact spring I 44 with its ends I46 slidable in apertures I48 in the point I42. A spring I50 acts between the diaphragm I2I and the bushing I32. A metal bracket I52 is secured atone end to' the bushing I32 for attachment to the wheel As pressure in the tire increases. the diaphragm I2I is'pushed to the right, 'forcing the point I42 into insulating bushing I36 and squeezing its spring I 44 out of contact with the bushing I32,'thus breaking the As the tire pressure returns to normal, the rod I40 assumes the position shown in Figure 5, allowing current to flow through a wire I54 and the rod I40 through the spring ends I46 to bushing I32 and out through bracket I52, so as to actuate a warning lamp connected with a battery to, the bracket I 52 and wire I54.

Dished half I I8 carries an outlet valve stem with a conventional valve core and pin I58. A bodymember I60 having an axial bore I62 is threaded onto the valve stem. A plunger shaft upward by air pressure, allowing some of the air to escape through hole I14, and thus reducing tire' pressure.

Although I havedescribed a preferred embodiment of my invention in specific terms, it is to be understood that numerous changes may be made in size, shape, material and arrangement without departing from the spirit and scope of the invention as claimed.

I claim: a I In a signaling device for indicating a change in pressure of a pneumatic tire tube, including an air-pressure-actuated means operatively con nected to a tire tube for actuating an electric switch, the improvement comprising an electric switch including astationary and a movable contact, said stationary contact comprising a tubular sleeve of current-conducting material, and a tubular bushing of' insulating material, said bushing lining a portion of theinner periphery ofsaid sleeve and merging with an unlined portion thereof toprovide an annular shoulder, said movable contact comprising a plunger axially disposed in said sleeve, means operatively connecting said plunger to said pressure-actuated means whereby to reciprocate said plunger axially in said sleeve, said plunger including a head, said head being formed With a substantially radiallydirected aperture therein, a radially outwardlyloaded contact spring fixed to said head, said spring including an outwardly-directed portion and a free end, said free end being slidable in said aperture, said plunger and head being nor-- mally. positioned in said sleeve with said outwardly-direct'ed portion of said spring in engagement with said unlined portion of said sleeve whereby to provide a normally closed switch, and said plunger being movable by said pressureactuated means ina direction to engage said REFERENCES CITED The following references are of record in the file of this patent:

I UNITED STATES PATENTS Number Name Date 1 1,183,486 Pardue May 16, 1916 1,410,297 Harman Mar. 21, 1922 1,657,406 McGuire Jan. 24, 1928 1,960,662 Como et a1 May 29, 1934 2,113,957 Androsky Apr. 12, 1938 2,260,246

Woodrufi et al Oct. 21, 1941 

